Patent application title: METHODS AND SYSTEMS FOR GENERATING POLYOLS

Abstract:

Disclosed are methods for generating propylene glycol, ethylene glycol and
other polyols, diols, ketones, aldehydes, carboxylic acids and alcohols
from biomass using hydrogen produced from the biomass. The methods
involve reacting a portion of an aqueous stream of a biomass feedstock
solution over a catalyst under aqueous phase reforming conditions to
produce hydrogen, and then reacting the hydrogen and the aqueous
feedstock solution over a catalyst to produce propylene glycol, ethylene
glycal and the other polyols, diols, ketones, aldehydes, carboxylic acids
and alcohols. The disclosed methods can be run at lower temperatures and
pressures, and allows for the production of oxygenated hydrocarbons
without the need for hydrogen from an external source.

Claims:

1. A method of generating ketones or alcohols, the method comprising the
steps of:a. contacting a first catalytic material comprising one or more
Group VIII metals with a first portion of an aqueous feedstock solution
comprising water and at least one water-soluble oxygenated hydrocarbon
having two or more carbon atoms under conditions sufficient to produce
hydrogen; andb. reacting the hydrogen with a second portion of the
aqueous feedstock solution over a second catalytic material, the second
catalytic material different than the first catalytic material and
comprising iron, ruthenium, copper, rhenium, cobalt, nickel, an alloy of
at least two of the foregoing, or mixtures of at least two of the
foregoing, under conditions sufficient to produce one or more ketones
selected from the group consisting of acetone, propanone, butanone,
pentanone, and hexanone, or one or more alcohols selected from the group
consisting of methanol, ethanol, iso-propyl alcohol, propanol, butanol,
pentanol, and hexanol.

2. The method of claim 1 further comprising the step of adding a
supplemental hydrogen to react with at least a portion of the second
portion of the aqueous feedstock solution.

3. The method of claim 1, wherein the first catalytic material contacts
the first portion of the aqueous feedstock at:a. a temperature of about
80.degree. C. to 400.degree. C.; andb. a pressure where at least a
portion of the water and the oxygenated hydrocarbons are condensed
liquids.

4. The method of claim 1, wherein the hydrogen reacts with a second
portion of the feedstock solution at:a. a temperature of about
100.degree. C. to 300.degree. C.; andb. a pressure of about 72 psig to
about 1300 psig.

5. The method of claim 1, wherein the second portion of the feedstock
solution further comprises oxygenated hydrocarbons formed by contacting
the feedstock solution with the first catalytic material.

6. The method of claim 1, wherein the second portion of the feedstock
solution is contacted with the hydrogen and the second catalytic material
at a pressure greater than about 365 psig.

7. The method of claim 1, wherein the molar ratio of the first catalytic
material to the second catalytic material is about 5:1 to 1:5.

8. The method of claim 1, wherein the first catalytic material comprises
at least one transition metal selected from the group consisting of
platinum, nickel, palladium, ruthenium, rhodium, rhenium, iridium, an
alloy of at least two of the foregoing, and mixtures of at least two of
the foregoing.

9. The method of claim 1, wherein the second catalytic material is
selected from the group consisting of iron, nickel, rhenium, ruthenium,
and cobalt.

10. The method of claim 1, wherein the first catalytic material and the
second catalytic material are combined in a catalytic mixture.

11. The method of claim 10, wherein the first catalytic material comprises
at least one transition metal selected from the group consisting of:
platinum, nickel, palladium, ruthenium, rhodium, rhenium, iridium, an
alloy of at least two of the foregoing and mixtures of at least two of
the foregoing; and the second catalytic metal is iron or rhenium.

12. The method of claim 11, wherein the first catalytic material is
platinum and the second catalytic material is rhenium.

13. The method of claim 10, wherein the first portion of the feedstock
solution and the second portion of the feedstock solution are contacted
with the first catalytic material and the second catalytic material in a
reactor vessel at a temperature of about 200.degree. C. to 270.degree. C.

14. The method of claim 10, wherein the catalytic mixture is adhered to a
support.

15. The method of claim 14, wherein the support is selected from the group
consisting of carbon, silica, silica-alumina, alumina, zirconia, titania,
ceria, vanadia, and mixtures thereof.

16. The method of claim 15, wherein the support is an activated carbon.

17. The method of claim 15, wherein the support comprises zirconia.

18. The method of claim 1, wherein the first portion of the feedstock
solution is contacted with the first catalytic material at a temperature
of about 150.degree. C. to 270.degree. C. and the second portion of the
feedstock solution is contacted with the second catalytic material at a
temperature of about 200.degree. C. to 270.degree. C.

19. A method of generating ketones or alcohols, the method comprising the
steps of:a. contacting a first catalytic material comprising one or more
Group VIII metals with a first portion of an aqueous feedstock solution
comprising water, a recycle stream and at least one water-soluble
oxygenated hydrocarbon having two or more carbon atoms under conditions
sufficient to produce hydrogen; andb. reacting the hydrogen with a second
portion of the aqueous feedstock solution over a second catalytic
material, the second catalytic material different than the first
catalytic material and selected from the group consisting of: iron,
ruthenium, copper, rhenium, cobalt, nickel, an alloy of at least two of
the foregoing, and mixtures of at least two of the foregoing, under
conditions sufficient to produce an effluent stream comprising unreacted
oxygenated hydrocarbons, byproducts and one or more ketones selected from
the group consisting of acetone, propanone, butanone, pentanone, and
hexanone, or one or more alcohols selected from the group consisting of
methanol, ethanol, iso-propyl alcohol, propanol, butanol, pentanol, and
hexanol; andc. separating at least a portion of the unreacted oxygenated
hydrocarbons and byproducts from the effluent stream into the recycle
stream; andd. mixing at least a portion of the recycle stream with one or
more water-soluble oxygenated hydrocarbons to provide the aqueous
feedstock solution.

20. The method of claim 19 further comprising the step of adding a
supplemental hydrogen to react with at least a portion of the second
portion of the aqueous feedstock solution.

21. The method of claim 19, wherein the first catalytic material contacts
the first portion of the aqueous feedstock at:a. a temperature of about
80.degree. C. to 400.degree. C.; andb. a pressure where at least a
portion of the water and the oxygenated hydrocarbons are condensed
liquids.

22. The method of claim 19, wherein the hydrogen reacts with a second
portion of the feedstock solution at:a. a temperature of about
100.degree. C. to 300.degree. C.; andb. a pressure of about 72 psig to
about 1300 psig.

23. The method of claim 19, wherein the second portion of the feedstock
solution is contacted with the hydrogen and the second catalytic material
at a pressure greater than about 365 psig.

24. The method of claim 19, wherein the molar ratio of the first catalytic
material to the second catalytic material is about 5:1 to 1:5.

25. The method of claim 19, wherein the first catalytic material comprises
at least one transition metal selected from the group consisting of
platinum, nickel, palladium, ruthenium, rhodium, rhenium, iridium, an
alloy of at least two of the foregoing, and mixtures of at least two of
the foregoing.

26. The method of claim 19, wherein the second catalytic material is
selected from the group consisting of iron, nickel, rhenium, ruthenium,
and cobalt.

27. The method of claim 19, wherein the first catalytic material and the
second catalytic material are combined in a catalytic mixture.

28. The method of claim 27, wherein the first catalytic material comprises
at least one transition metal selected from the group consisting of:
platinum, nickel, palladium, ruthenium, rhodium, rhenium, iridium, an
alloy of at least two of the foregoing and mixtures of at least two of
the foregoing; and the second catalytic metal is iron or rhenium.

29. The method of claim 27, wherein the first catalytic material is
platinum and the second catalytic material is rhenium.

30. The method of claim 27, wherein the first catalytic material and the
second catalytic material are adhered to a support.

31. The method of claim 30, wherein the support is selected from the group
consisting of carbon, silica, silica-alumina, alumina, zirconia, titania,
ceria, vanadia, and mixtures thereof.

32. The method of claim 31, wherein the support is an activated carbon.

33. The method of claim 31, wherein the support comprises zirconia.

34. The method of claim 19, wherein the first portion of the feedstock
solution is contacted with the first catalytic material at a temperature
of about 150.degree. C. to 270.degree. C. and the second portion of the
feedstock solution is contacted with the second catalytic material at a
temperature of about 200.degree. C. to 270.degree. C.

35. A method of generating ketones or alcohols, the method comprising the
steps of:a. contacting a first catalytic material comprising one or more
Group VIII metals with a first portion of an aqueous feedstock solution
comprising water and at least one water-soluble oxygenated hydrocarbon
having two or more carbon atoms under conditions sufficient to produce
aqueous phase reforming (APR) hydrogen; andb. reacting the APR hydrogen
and a supplemental hydrogen with a second portion of the aqueous
feedstock solution over a second catalytic material, the second catalytic
material different than the first catalytic material and comprising iron,
ruthenium, copper, rhenium, cobalt, nickel, an alloy of at least two of
the foregoing, or mixtures of at least two of the foregoing, under
conditions sufficient to produce one or more ketones selected from the
group consisting of acetone, propanone, butanone, pentanone, and
hexanone, or one or more alcohols selected from the group consisting of
methanol, ethanol, iso-propyl alcohol, propanol, butanol, pentanol, and
hexanol.

36. The method of claim 35, wherein the first catalytic material contacts
the first portion of the aqueous feedstock at:a. a temperature of about
80.degree. C. to 400.degree. C.; andb. a pressure where at least a
portion of the water and the oxygenated hydrocarbons are condensed
liquids.

37. The method of claim 35, wherein the APR hydrogen and the supplemental
hydrogen react with a second portion of the feedstock solution at:a. a
temperature of about 100.degree. C. to 300.degree. C.; andb. a pressure
of about 72 psig to about 1300 psig.

38. The method of claim 35, wherein the second portion of the feedstock
solution is contacted with the APR hydrogen, the supplemental hydrogen
and the second catalytic material at a pressure greater than about 365
psig.

39. The method of claim 35, wherein the molar ratio of the first catalytic
material to the second catalytic material is about 5:1 to 1:5.

40. The method of claim 35, wherein the first catalytic material comprises
at least one transition metal selected from the group consisting of
platinum, nickel, palladium, ruthenium, rhodium, rhenium, iridium, an
alloy of at least two of the foregoing, and mixtures of at least two of
the foregoing.

41. The method of claim 35, wherein the second catalytic material is
selected from the group consisting of iron, nickel, rhenium, ruthenium,
and cobalt.

42. The method of claim 35, wherein the first catalytic material and the
second catalytic material are combined in a catalytic mixture.

43. The method of claim 42, wherein the first catalytic material and
second catalytic material are adhered to a support.

44. The method of claim 43, wherein the support is selected from the group
consisting of carbon, silica, silica-alumina, alumina, zirconia, titania,
ceria, vanadia, and mixtures thereof.

Description:

RELATED APPLICATIONS

[0001]This application is a continuation of U.S. application Ser. No.
11/800,671 filed May 7, 2007, which claimed the benefit of U.S.
provisional application 60/798,484 filed May 8, 2006. Each application is
incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0003]The present invention is directed to methods, catalysts and reactor
systems for generating one or more oxygenated hydrocarbon products from
an aqueous feedstock stream containing a water-soluble oxygenated
hydrocarbon. Preferably, the reaction products include diols and other
polyols, ketones, aldehydes, carboxylic acids and/or alcohols produced by
hydrogenating water-soluble polyols (such as glycerol) in a
biomass-derived feedstock using hydrogen produced within a reactor system
from a portion of the biomass feedstock stream.

BACKGROUND

[0004]Biomass (material derived from living or recently living biological
materials) is becoming one of the most important renewable energy
resources. The ability to convert biomass to fuels, chemicals, energy and
other materials is expected to strengthen rural economies, decrease
dependence on oil and gas resources, and reduce air and water pollution.
The generation of energy and chemicals from renewable resources such as
biomass also reduces the net rate of carbon dioxide production, an
important greenhouse gas that contributes to global warming.

[0005]A key challenge for promoting and sustaining the use of biomass in
the industrial sector is the need to develop efficient and
environmentally benign technologies for converting biomass to useful
products. Present biomass conversion technologies unfortunately tend to
carry additional costs which make it difficult to compete with products
produced through the use of traditional resources, such as fossil fuels.
Such costs often include capital expenditures on equipment and processing
systems capable of sustaining extreme temperatures and high pressures,
and the necessary operating costs of heating fuels and reaction products,
such as fermentation organisms, enzymatic materials, catalysts and other
reaction chemicals.

[0006]One alternative fuel technology receiving significant attention is
biodiesel produced via the esterification of vegetable oils or animal
fats. The US production of biodiesel is reaching 30-40 million gallons
annually, but is projected to grow to a targeted 400 million gallons of
production per year by 2012. In Europe, over 1.4 metric tons of biodiesel
was produced in 2003, and major initiatives are underway in Brazil and
Asia.

[0007]A byproduct of the biodiesel process is crude glycerol, which has
little or no value without further refinement. The issue is what to do
with the escalating supply of crude glycerol. Purification of crude
glycerol is one option, however, the refining of crude glycerol, which
contains catalyst, organic impurities and residual methanol, is difficult
and often too expensive for small scale biodiesel producers. To
complicate matters, the demand for pure glycerol has also remained static
and prices have dropped dramatically as more supply is brought on line,
especially in Europe.

[0008]The development of effective methods to convert crude glycerol to
alternative products, such as diols and other polyols, ketones,
aldehydes, carboxylic acids and alcohols, may provide additional
opportunities to improve the cost effectiveness and environmental
benefits of biodiesel production. For example, over a billion pounds of
propylene glycol is produced in the United States today and used in the
manufacture of many industrial products and consumer products, including
aircraft and runway deicing fluids, antifreeze, coolants, heat transfer
fluids, solvents, flavors and fragrances, cosmetic additives,
pharmaceuticals, hydraulic fluids, chemical intermediates, and in
thermoset plastics. Propylene glycol is currently produced via the
partial oxidation of fossil fuel derived propylene to form propylene
oxide, which is then reacted with water to form propylene glycol.

[0009]Researchers have recently developed methods to react pure hydrogen
with larger biomass-derived polyols (glycerol, xylitol, and sorbitol) and
sugars (xylose and glucose) over hydrogenation and hydrogenolysis
catalytic materials to generate propylene glycol. While the biomass is
derived from a renewable source, the pure hydrogen itself is generally
derived through the steam reforming of non-renewable natural gas. Due to
its origin, the pure hydrogen must also be transported to and introduced
into the production stream at elevated pressures from an external source,
thereby decreasing the efficiency of the process and causing an increase
in the overall cost of the ultimate end-product.

[0010]For instance, U.S. Pat. Nos. 6,841,085, 6,677,385 and 6,479,713 to
Werpy et al., disclose methods for the hydrogenolysis of both
carbon-oxygen and carbon-carbon bonds using a rhenium (Re)-containing
multimetallic catalyst in the presence of external hydrogen to produce
products such as propylene glycol (PG). The Re-containing catalyst may
also include Ni, Pd, Ru, Co, Ag, Au, Rh, Pt, Ir, Os and Cu. The
conversion takes place at temperatures in a range from 140° C. to
250° C., and more preferably 170° C. to 220° C., and
a hydrogen pressure between 600 psi to 1600 psi hydrogen.

[0011]Dasari et al. also disclose hydrogenolysis of glycerol to PG in the
presence of hydrogen from an external source, at temperatures in a range
from 150° C. to 260° C. and a hydrogen pressure of 200 psi,
over nickel, palladium, platinum, copper and copper-chromite catalysts.
The authors reported increased yields of propylene glycol with decreasing
water concentrations, and decreasing PG selectivity at temperatures above
200° C. and hydrogen pressures of 200 psi. The authors further
reported that nickel, ruthenium and palladium were not very effective for
hydrogenating glycerol. Dasari, M. A.; Kiatsimkul, P.-P.; Sutterlin, W.
R.; Suppes, G. J. Low-pressure hydrogenolysis of glycerol to propylene
glycol Applied Catalysis, A: General, 281(1-2), p. 225 (2005).

[0012]U.S. patent application Ser. No. 11/088,603 (Pub. No. US2005/0244312
A1) to Suppes et al., disclose a process for converting glycerin into
lower alcohols having boiling pointes less than 200° C., at high
yields. The process involves the conversion of natural glycerin to
propylene glycol through an acetol intermediate at temperatures from
150° C. to 250° C., at a pressure ranging from 1 to 25 bar
(14.5 to 363 psi), and preferably from 5 to 8 bar (72.5 to 116 psi), over
a palladium, nickel, rhodium, zinc, copper, or chromium catalyst. The
reaction occurs in the presence or absence of hydrogen, with the hydrogen
provided by an external source. The glycerin is reacted in solution
containing 50% or less by weight water, and preferably only 5% to 15%
water by weight.

SUMMARY

[0013]The present invention is directed to methods for generating
oxygenated hydrocarbons, such as polyols, diols, ketones, aldehydes,
carboxylic acids and alcohols, from an aqueous feedstock solution using
hydrogen produced from a portion of the feedstock solution. The method
involves the reaction of a portion of the feedstock solution over a first
catalyst under aqueous phase reforming conditions to produce hydrogen,
and reacting the hydrogen with at least a second portion of the feedstock
solution over a second catalyst under conditions appropriate to produce
the desired products (e.g., by hydrogenation). In one embodiment, the
method includes the steps of (a) contacting a first catalytic material
with an aqueous feedstock solution containing water and at least one
water soluble oxygenated hydrocarbon having two or more carbon atoms to
produce hydrogen, and (b) reacting the hydrogen with the remaining
oxygenated hydrocarbons over a second catalytic material selected to
promote the hydrogenation of the oxygenated hydrocarbons to the desired
reactant products.

[0014]The aqueous feedstock solution preferably includes water and an
oxygenated hydrocarbon having at least two carbon atoms, such as any one
of a number of polyols, sugars, sugar alcohols, alcohols, starches,
lignins, cellulosics and water soluble saccharides. Preferably, the
feedstock solution includes glycerol.

[0015]The first catalytic material is desirably a heterogeneous catalyst
having one or more materials capable of producing hydrogen under aqueous
phase reforming conditions, such as Group VIIIB metals, whether alone or
in combination with Group VIIB metals, Group VIB metals, Group VB metals,
Group IVB metals, Group JIB metals, Group IB metals, Group IVA metals, or
Group VA metals. The second catalytic material is preferably a
heterogeneous catalyst having one or more materials capable of catalyzing
a reaction between the generated hydrogen and the feedstock solution to
produce diols or other polyols, ketones, aldehydes, carboxylic acids
and/or alcohols. Preferred examples of the second catalytic material
include copper Group VIII metals, mixtures and alloys thereof, and
various bifunctional catalysts. The second catalytic material may include
these metals alone or in combination with one or more Group VIIIB, VIIB
metals, Group VIB metals, Group VB metals, Group IVB metals, Group IIB
metals, Group IB metals, Group WA metals, or Group VA metals. Preferably,
the second catalytic material includes iron, ruthenium, copper, rhenium,
cobalt or nickel.

[0016]In one embodiment, polyols, diols, ketones, aldehydes, carboxylic
acids and/or alcohols are generated by producing hydrogen from a portion
of the aqueous feedstock solution placed in contact with a first
catalytic material at a temperature from about 80° C. to
400° C., a weight hourly space velocity (WHSV) of at least about
1.0 gram of oxygenated hydrocarbon per gram of first catalytic material
per hour and a pressure where the water and the oxygenated hydrocarbons
are condensed liquids, and then reacting the hydrogen with a second
portion of the feedstock solution over a second catalytic material under
conditions of temperature, pressure and weight hourly space velocity
effective to produce one or more oxygenated hydrocarbons, such as diols
and other polyols, ketones, aldehydes, carboxylic acids and/or alcohols.
The second portion of the feedstock solution will generally include both
original oxygenated hydrocarbons and oxygenated hydrocarbons resulting
from the hydrogen production step, and may be contacted with the second
catalytic material at a temperature from about 100° C. to
300° C., a pressure from about 200 psig to about 1200 psig and a
weight hourly space velocity of at least about 1.0 gram of oxygenated
hydrocarbon per gram of catalytic material per hour per hour. The
resulting composition may generally include, without limitation, a
multiphase composition of matter having a solid phase with a catalyst
composition containing the first catalytic material and the second
catalytic material, preferably platinum and iron, and a fluid phase
containing water, glycerol, carboxylic acid, propylene glycol and carbon
dioxide.

[0017]In another embodiment, reactor systems are provided for producing
oxygenated compounds, such as diols or other polyols, ketones, aledhydes,
carboxylic acids and/or alcohols, from a polyol. The reactor system
includes at least a first reactor bed adapted to receive an aqueous
feedstock solution to produce hydrogen and a second reactor bed adapted
to produce the oxygenated compounds from the hydrogen and a portion of
the feedstock solution. The first reactor bed is configured to contact
the aqueous feedstock solution in a condensed phase with a first
catalytic material (described above) to provide hydrogen in a reactant
stream. The second reactor bed is configured to receive the reactant
stream for contact with a second catalytic material (described above) and
production of the desired oxygenated compounds. In one preferred
embodiment, the first catalytic material includes a Group VIII metal,
while the second catalytic material is either iron, ruthenium, copper,
rhenium, cobalt, nickel or alloys or mixtures thereof. The second reactor
bed may be positioned within the same reactor vessel along with the first
reaction bed or in a second reactor vessel in communication with a first
reactor vessel having the first reaction bed. The reactor vessel
preferably includes an outlet adapted to remove the product stream from
the reactor vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a graph depicting the thermodynamics (ΔG°/RT
versus temperature) for the production of CO and H2 from vapor-phase
reforming of CH4, C2H6, C3H8 and
C6H14; CH3(OH), C2H4(OH)2,
C3H5(OH)3 and C6H8(OH)6; and water-gas
shift. Dotted lines show values of ln(P) for the vapor pressures versus
temperature of CH3(OH), C2H4(OH)2,
C3H5(OH)3, and C6H8(OH)6 (pressure in units
of atm).

[0019]FIG. 2 is a reaction schematic depicting reaction pathways for the
production of H2 and propylene glycol from glycerol.

[0020]FIG. 3 is a reaction schematic depicting reaction pathways for the
production of H2 and propyl alcohol from glycerol.

[0021]FIG. 4 is a reaction schematic depicting reaction pathways for the
production of H2 and hexanol from sorbitol.

[0022]FIG. 5 is a schematic diagram illustrating a process for converting
a polyol to a diol or alcohol using in-situ generated hydrogen.

[0023]FIG. 6 is a schematic diagram illustrating a process for generating
reaction products from a polyol using a reactor having a first reaction
chamber for generating hydrogen and a second hydrogenation chamber.

[0024]FIG. 7 is a schematic diagram illustrating a process for generating
reaction products from a polyol with an added supplement using a reactor
having a first reaction chamber for generating hydrogen and a second
hydrogenation chamber.

[0025]FIG. 8 is a schematic diagram of a reactor system that can be used
to evaluate the generation of polyols from glycerol via aqueous-phase
reforming; and

[0026]FIG. 9 is a graph depicting the distribution of carbon products
during aqueous phase reforming of glycerol over a modified platinum
catalyst.

DETAILED DESCRIPTION

[0027]The present disclosure relates to methods and systems for reforming
concentrations of biomass with water at low temperatures to produce
propylene glycol, ethylene glycol and other polyols, diols, ketones,
aldehydes, carboxylic acids and/or alcohols using in-situ generated
hydrogen. The hydrogen may be generated by reacting a portion of an
aqueous feedstock solution containing the biomass and water over a
catalyst under aqueous phase reforming (APR) conditions. The hydrogen
generated by APR may then be used to react with a second portion of the
feedstock solution, including the oxygenated hydrocarbons derived from
the production of the APR hydrogen, over a second catalyst under
conditions appropriate to produce the desired products.

[0031]"Space Velocity"=the mass/volume of reactant per unit of catalyst
per unit of time.

[0032]"TOF"=turnover frequency.

[0033]"WHSV"=weight hourly space velocity=mass of oxygenated compound per
mass of catalyst per hour.

[0034]"WGS"=water-gas shift.

[0035]Aqueous-Phase Reforming (APR) is a catalytic reforming process that
generates hydrogen-rich fuels from oxygenated compounds derived from
biomass (glycerol, sugars, sugar alcohols, etc.). Various APR methods and
techniques are described in U.S. Pat. Nos. 6,699,457; 6,964,757 and
6,964,758; and U.S. patent application Ser. No. 11;234,727 (all to
Cortright et al., and entitled "Low-Temperature Hydrogen Production from
Oxygenated Hydrocarbons"); and U.S. Pat. No. 6,953,873 (to Cortright et
al., and entitled "Low Temperature Hydrocarbon Production from Oxygenated
Hydrocarbons"); and commonly owned co-pending International Patent
Application No. PCT/US2006/048030 (to Cortright et al., and entitled
"Catalyst and Methods for Reforming Oxygenated Compounds"), all of which
are incorporated herein by reference. The term "aqueous phase reforming"
and "APR" shall generically denote the overall reaction of an oxygenated
compound and water to yield a hydrogen stream, regardless of whether the
reactions takes place in the gaseous phase or in the condensed liquid
phase. Where the distinction is important, it shall be so noted. "APR
hydrogen" shall generically refer to the hydrogen produced by the APR
process.

[0036]The APR process is preferably performed in the liquid phase,
although it may also be carried out in a vapor phase reaction. APR can
occur at temperatures where the water-gas shift reaction is favorable
(e.g., 80° C. to 400° C.), making it possible to generate
hydrogen with low amounts of CO in a single chemical reactor. Advantages
of the APR process include: (i) the performance of the reaction at lower
pressures (typically at 200 to 725 psig); (ii) the ability to generate a
hydrogen-rich feedstock at lower temperatures without the need to
volatilize water, which provides a major energy savings; (iii) the
ability to operate at temperatures that minimize undesirable
decomposition reactions typically encountered when carbohydrates are
heated to elevated temperatures; and (iv) the utilization of agricultural
derived feedstocks. The APR process takes advantage of the unique
thermodynamic properties of oxygenated compounds having a favorable
carbon-to-oxygen stoichiometry, especially hydrocarbons having a C:O
ratio of 1:1 (the preferred ratio), to generate hydrogen at relatively
low temperatures in a single reaction step.

[0037]The stoichiometric reaction for reforming an oxygenated hydrocarbon
having a C:O ratio of 1:1 to produce CO and H2 is given by reaction
1.

CnH2yOnnCO+yH2 (1)

[0038]Reaction conditions for producing hydrogen from hydrocarbons can be
dictated by the thermodynamics for the steam reforming of alkanes to form
CO and H2 (reaction 2), and the water-gas shift reaction to form
CO2 and H2 from CO (reaction 3).

CnH2n+2+nH2OnCO+(2n+1)H2 (2)

CO+H2OCO2+H2 (3)

[0039]FIG. 1 (constructed from thermodynamic data obtained from Chemical
Properties Handbook, C. L. Yaws, McGraw Hill, 1999) shows changes in the
standard Gibbs free energy (ΔG°/RT) associated with equation
2 for a series of alkanes (CH4, C2H6, C3H8,
C6H14), normalized per mole of CO produced. It can be seen that
the steam reforming of alkanes is thermodynamically favorable (i.e.,
negative values of ΔG°/RT) only at temperatures higher than
675 K (402° C.).

[0040]Relevant oxygenated hydrocarbons having a C:O ratio of 1:1, such as
methanol (CH3OH), ethylene glycol (C2H4(OH)2),
glycerol (C3H5(OH)3), and sorbitol
(C6H8(OH)6), are also illustrated. On FIG. 1, dotted lines
show values of ln(P) for the vapor pressures versus temperature of
CH3(OH), C2H4(OH)2, C3H5(OH)3, and
C6H8(OH)6 (pressure in units of atm). FIG. 1 shows that
steam reforming of these oxygenated hydrocarbons to produce CO and
H2 is thermodynamically favorable at significantly lower
temperatures than those required for alkanes with similar numbers of
carbon atoms. FIG. 1 also shows that the value of ΔG°/RT for
water-gas shift of CO to CO2 and H2 is more favorable at
similarly low temperatures. Consequently, it is possible to reform
oxygenated hydrocarbons with favorable C:O ratios at low-temperatures to
form CO and H2, and subsequently H2 and CO2, in a
single-step catalytic process.

[0041]While FIG. 1 shows that the conversion of oxygenated compounds in
the presence of water to H2 and CO2 is highly favorable at low
temperatures, the subsequent reaction of H2 and oxygenated compounds
to form alkanes (CnH2n+2) and water is also highly favorable at
low temperatures.

CO2+4H2CH4+2H2O (4)

[0042]In a first embodiment, methods for generating oxygenated compounds
are provided. The methods preferably include the steps of (a) contacting
a first catalytic material with a first portion of an aqueous feedstock
solution containing water and water soluble oxygenated hydrocarbons to
form APR hydrogen, and (b) contacting the APR hydrogen and a second
portion of the feedstock solution over a second catalytic material to
produce a reaction product that includes, without limitation, a polyol,
diol, ketone, aldehyde, carboxylic acid and/or alcohol. The second
portion of the feedstock solution preferably includes oxygenated
hydrocarbons derived from the production of the APR hydrogen in addition
to oxygenated hydrocarbons included in the original feedstock solution,
but may also include portions of the feedstock solution without
oxygenated hydrocarbons generated during APR hydrogen formation. The
first catalytic material is preferably an aqueous phase reforming (APR)
catalyst, and the second catalytic material is preferably a material
capable of catalyzing hydrogenation reactions. Unless otherwise
indicated, any discussion of hydrogenation catalysts and APR catalysts
herein are non-limiting examples of suitable catalytic materials.

[0043]As described more fully below, the more thermodynamically favored
reaction consumes APR hydrogen to yield a mixture of polyols, diols,
ketones, aldehydes and/or alcohols. Under favorable conditions, the
processes and reactor systems described below may yield a mixture
predominantly comprising one or more oxygenated compounds, such as diols
and other polyols, ketones, aldehydes, carboxylic acids and/or alcohols.
For example, processes and reactor systems described herein may provide a
carbon containing reaction product with more than 50% of one or more
polyols, such as propylene glycol. Preferably, substantially all of the
APR hydrogen generated in-situ by the APR process is consumed during the
reaction with the oxygenated hydrocarbons over the second catalytic
material, without the addition of pure hydrogen from an external source.

[0044]FIGS. 2, 3 and 4 show schematic representations of possible reaction
pathways for the formation of both H2 and polyols, diols, ketones
and alcohols from oxygenated hydrocarbons over a metal catalyst. In
general, hydrogen formation involves dehydrogenation and subsequent
rearrangement steps that form intermediates containing carbon atoms
unbound to oxygen atoms. The carbohydrate first undergoes dehydrogenation
to provide adsorbed intermediates, prior to cleavage of C--C or C--O
bonds. Subsequent cleavage of C--C bonds leads to the formation of CO and
H2, with the CO then reacting with water to form CO2 and
H2 by the water-gas shift (WGS) reaction. The formation of polyols,
diols, ketones, carboxylic acids, aldehydes, and/or alcohols follows
where the hydroxyl groups of the oxygenated hydrocarbon are removed via a
dehydration mechanism with subsequent hydrogenation with the hydrogen
formed above. It's also possible to form polyols, diols, ketones and/or
alcohols on the metal catalyst by first cleaving C--O bonds in adsorbed
carbohydrate intermediates. The intermediates can then be converted to
the polyol, diol, ketone, carboxylic acid, aldehyde, and/or alcohol
depending on the catalyst and reaction conditions.

Feedstock Solution

[0045]The preferred feedstock includes water-soluble oxygenated
hydrocarbons derived from biomass. As used herein, the term "biomass"
refers to, without limitation, organic materials produced by plants (such
as leaves, roots, seeds and stalks), and microbial and animal metabolic
wastes. Common sources of biomass include: (1) agricultural wastes, such
as corn stalks, straw, seed hulls, sugarcane leavings, bagasse,
nutshells, and manure from cattle, poultry, and hogs; (2) wood materials,
such as wood or bark, sawdust, timber slash, and mill scrap; (3)
municipal waste, such as waste paper and yard clippings; and (4) energy
crops, such as poplars, willows, switch grass, alfalfa, prairie
bluestream, corn, soybean, and the like. The feedstock may be fabricated
from biomass by any means now known or developed in the future, or may be
simply byproducts of other processes, such as crude glycerol from
biodiesel production.

[0046]The oxygenated hydrocarbons may be any hydrocarbon having at least
two carbon atoms and at least one oxygen atom. In the preferred
embodiment, the oxygenated hydrocarbon is water-soluble and has from 2 to
12 carbon atoms, and more preferably from 2 to 6 carbon atoms. The
oxygenated hydrocarbon also preferably has an oxygen-to-carbon ratio
ranging from 0.5:1 to 1.5:1, including ratios of 0.75:1.0, 1.0:1.0,
1.25:1.0, 1.5:1.0 and other ratios there between. In the most preferred
embodiment, the oxygenated hydrocarbons have an oxygen-to-carbon ratio of
1:1. Nonlimiting examples of preferred water-soluble oxygenated
hydrocarbons include ethanediol, ethanedione, acetic acid, propanol,
propanediol, propionic acid, glycerol, glyceraldehyde, dihydroxyacetone,
lactic acid, pyruvic acid, malonic acid, butanediols, butanoic acid,
aldotetroses, tautaric acid, aldopentoses, aldohexoses, ketotetroses,
ketopentoses, ketohexoses, alditols, sugars, sugar alcohols, cellulosics,
lignocellulosics, saccharides, starches, polyols and the like. Most
preferably, the oxygenated hydrocarbon is sugar, sugar alcohols,
cellulose, saccharides and glycerol.

[0047]The oxygenated hydrocarbon is combined with water to provide an
aqueous feedstock solution having a concentration effective for causing
the formation of the desired reaction products. The water may be added
either prior to contacting the oxygenated hydrocarbon to the APR catalyst
or at the same time as contacting the oxygenated hydrocarbon to the APR
catalyst. In the preferred embodiment, the water is combined with the
oxygenated hydrocarbon to form an aqueous solution prior to contacting
the APR catalyst for easier processing, but it is also recognized that
the oxygenated hydrocarbon may also be placed into solution and then
supplemented with water at the time of contact with the APR catalyst to
form the aqueous feedstock solution. Preferably the balance of the
feedstock solution is water. In some embodiments, the feedstock solution
consists essentially of water, one or more oxygenated hydrocarbons and,
optionally, one or more feedstock modifiers described herein, such as
alkali or hydroxides of alkali or alkali earth salts or acids. The
feedstock solution may also contain negligible amounts of hydrogen,
preferably less than about 1 bar (14.5 psi). In the preferred
embodiments, hydrogen is not added to the feedstock.

[0048]The water-to-carbon ratio in the solution is preferably from about
0.5:1 to about 7:1, including ratios there between such as 1:1, 2:1, 3:1,
4:1, 5:1, 6:1, and any ratios there between. The feedstock solution may
also be characterized as a solution having at least 20 weight percent of
the total solution as an oxygenated hydrocarbon. For example, the
solution may include one or more oxygenated hydrocarbons, with the total
concentration of the oxygenated hydrocarbons in the solution being at
least about 20%, 30%, 40%, 50%, 60% or greater by weight, including any
percentages between, and depending on the oxygenated hydrocarbons used.
More preferably the feedstock solution includes at least about 20%, 30%,
40%, 50%, or 60% of glycerol by weight, including any percentages
between. Water-to-carbon ratios and percentages outside of the above
stated ranges are also included within the scope of this invention.

Hydrogen Production

[0049]The APR hydrogen is produced from the feedstock under aqueous phase
reforming conditions. The reaction temperature and pressure are
preferably selected to maintain the feedstock in the liquid phase.
However, it is recognized that temperature and pressure conditions may
also be selected to more favorably produce hydrogen in the vapor-phase.
In general, the APR reaction and subsequent hydrogenation reactions
should be carried out at a temperature at which the thermodynamics of the
proposed reaction are favorable. The pressure will vary with the
temperature. For condensed phase liquid reactions, the pressure within
the reactor must be sufficient to maintain the reactants in the condensed
liquid phase at the reactor inlet.

[0050]For vapor phase reactions, the reaction should be carried out at a
temperature where the vapor pressure of the oxygenated hydrocarbon
compound is at least about 0.1 atm (and preferably a good deal higher),
and the thermodynamics of the reaction are favorable. This temperature
will vary depending upon the specific oxygenated hydrocarbon compound
used, but is generally in the range of from about 100° C. to about
450° C. for reactions taking place in the vapor phase, and more
preferably from about 100° C. to about 300° C. for vapor
phase reactions.

[0051]For liquid phase reactions, the reaction temperature may be from
about 80° C. to about 400° C., and the reaction pressure
from about 72 psig to about 1300 psig. Preferably, the reaction
temperature is between about 120° C. and about 300° C., and
more preferably between about 150° C. and about 270° C. The
reaction pressure is preferably between about 72 and 1200 psig, or
between about 145 and 1200 psig, or between about 200 and 725 psig, or
between about 365 and 600 psig. Because the hydrogen is produced in-situ,
the pressure is provided by a pumping mechanism that also drives the
feedstock solution through the reactor system.

[0052]The condensed liquid phase method may also optionally be performed
using a modifier that increases the activity and/or stability of the
first and/or the second catalytic material(s) (i.e., the catalyst
system). It is preferred that the water and the oxygenated hydrocarbon
are reacted at a suitable pH of from about 1.0 to about 10.0, including
pH values in increments of 0.1 and 0.05 between, and more preferably at a
pH of from about 4.0 to about 10.0. Generally, the modifier is added to
the feedstock solution in an amount ranging from about 0.1% to about 10%
by weight as compared to the total weight of the catalyst system used,
although amounts outside this range are included within the present
invention.

[0053]Alkali or alkali earth salts may also be added to the feedstock
solution to optimize the proportion of hydrogen in the reaction products.
Examples of suitable water-soluble salts include one or more selected
from the group consisting of an alkali or an alkali earth metal
hydroxide, carbonate, nitrate, or chloride salt. For example, adding
alkali (basic) salts to provide a pH of about pH 4.0 to about pH 10.0 can
improve hydrogen selectivity of reforming reactions.

[0054]The addition of acidic compounds may also provide increased
selectivity to the desired reaction products in the hydrogenation
reactions described below. It is preferred that the water-soluble acid is
selected from the group consisting of nitrate, phosphate, sulfate, and
chloride salts, and mixtures thereof. If an optional acidic modifier is
used, it is preferred that it be present in an amount sufficient to lower
the pH of the aqueous feed stream to a value between about pH 1.0 and
about pH 4.0. Lowering the pH of a feed stream in this manner may
increase the proportion of diols, polyols, ketones, carboxylic acids,
aldehydes, alcohols or alkanes in the final reaction products.

[0055]In general, the reaction should be conducted under conditions where
the residence time of the feedstock solution over the APR catalyst is
appropriate to generate an amount of APR hydrogen sufficient to react
with a second portion of the feedstock solution over the hydrogenation
catalyst to provide the desired products. For example, in one embodiment,
the WHSV for the reaction may be at least about 1.0 gram of oxygenated
hydrocarbon per gram of APR catalyst, and preferably between about 1.0 to
5.0 grams of oxygenated hydrocarbon per gram of APR catalyst, and more
preferably between about 1.9 to 4.0 grams of oxygenated hydrocarbon per
gram of APR catalyst.

APR Catalyst

[0056]The first catalytic material is preferably an APR catalyst,
typically a heterogeneous catalyst capable of catalyzing the reaction of
water and oxygenated hydrocarbons to form hydrogen under the conditions
described above. The preferred APR catalyst includes at least one Group
VIIIB transition metal, and any alloy or mixtures thereof. Preferably,
the APR catalyst includes at least one Group VIIIB transition metal in
combination with at least one second metal selected from Group VIIIB,
Group VIIB, Group VIB, Group VB, Group IVB, Group IIB, Group IB, Group
IVA or Group VA metals. The preferred Group VIIB metal includes rhenium,
manganese, or combinations thereof. The preferred Group VIB metal
includes chromium, molybedum, tungsten, or a combination thereof. The
preferred Group VIIIB metals include platinum, rhodium, ruthenium,
palladium, nickel, or combinations thereof.

[0057]Preferred loading of the primary Group VIIIB metal is in the range
of 0.25 wt % to 25 wt % on carbon, with weight percentages of 0.10% and
0.05% increments between, such as 1.00%, 1.10%, 1.15%, 2.00%, 2.50%,
5.00%, 10.00%, 12.50%, 15.00% and 20.00%. The preferred atomic ratio of
the second metal is in the range of 0.25-to-1 to 10-to-1, including
ratios there between, such as 0.50, 1.00, 2.50, 5.00, and 7.50-to-1.

[0058]A preferred catalyst composition is further achieved by the addition
of oxides of Group IIIB, and associated rare earth oxides. In such event,
the preferred components would be oxides of either lanthanium or cerium.
The preferred atomic ratio of the Group IIIB compounds to the primary
Group VIIIB metal is in the range of 0.25-to-1 to 10-to-1, including
ratios there between, such as 0.50, 1.00, 2.50, 5.00, and 7.50-to-1.

[0059]Unless otherwise specified, the recitation of an APR bimetallic
catalyst composition as "X:Y" herein, where X and Y are metals, refers to
a group of catalyst compositions comprising at least metals X and Y in
any suitable stoichoimetric combination, and optionally including other
materials. Similarly, the recitation of a catalyst composition as
"X1.0Y1.0" refers herein to a composition comprising at least metals X
and Y in a 1:1 stoichiometric molar ratio. Accordingly, particularly
preferred catalytic compositions are bimetallic metal compositions
described by the formula X:Y, where X is a Group VIIIB metal and Y is a
Group VIIIB, Group VIIB, Group VIB, Group VB, Group IVB, Group IIB, Group
IB, Group WA or Group VA metal. For example, the catalysts designated
"Re:Pt" include the bimetallic catalysts Re1.0Pt1.0 and
Re2.5Pt1.0. Furthermore, recitation of a bimetallic catalyst
X:Y can include additional materials besides X and Y, such as La or Ce.
For example, the catalysts designated "Re:Rh" herein include catalysts
such as Re1.0Rh1.0, Re1.0Rh3.8,
Re1.0Rh2.0Ce2.0, Re1.0Rh1.0Ce1.0, and
Re1.0Rh1.0La3.0.

[0060]In preferred embodiments, the catalyst system may include a support
suitable for suspending the catalyst in the feedstock solution. The
support should be one that provides a stable platform for the chosen
catalyst and the reaction conditions. The support may take any form which
is stable at the chosen reaction conditions to function at the desired
levels, and specifically stable in aqueous feedstock solutions. Such
supports include, without limitation, carbon, silica, silica-alumina,
alumina, zirconia, titania, ceria, vanadia and mixtures thereof.
Furthermore, nanoporous supports such as zeolites, carbon nanotubes, or
carbon fullerene may be utilized. Particularly useful catalyst systems
include, without limitation, platinum supported on silica, platinum
supported on silica-alumina, platinum supported on alumina, nickel
supported on silica-alumina, nickel supported on alumina, ruthenium
supported on silica-alumina, ruthenium supported on alumina, palladium
supported on silica-alumina, and nickel-platinum supported on
silica-alumina. In one embodiment, the APR catalyst system is platinum on
silica-alumina or silica, with the platinum being further alloyed or
admixed with nickel, ruthenium, copper, iron or rhenium. In another
embodiment, the APR catalyst system is nick on silica-alumina or silica,
with the nickel being further alloyed or admixed with copper, rhenium,
ruthenium or iron.

[0061]One particularly preferred catalyst support is carbon, especially
carbon supports having relatively high surface areas (greater than 100
square meters per gram). Such carbons include activated carbon
(granulated, powdered, or pelletized), activated carbon cloth, felts, or
fibers, carbon nanotubes or nanohorns, carbon fullerene, high surface
area carbon honeycombs, carbon foams (reticulated carbon foams), and
carbon blocks. The carbon may be produced via either chemical or steam
activation of peat, wood, lignite, coal, coconut shells, olive pits, and
oil based carbon. Another preferred support is granulated activated
carbon produced from coconuts.

[0062]The support may also be treated or modified to enhance its
properties. For example, the support may be treated, as by
surface-modification, to modify surface moieties, such as hydrogen and
hydroxyl. Surface hydrogen and hydroxyl groups can cause local pH
variations that affect catalytic efficiency. The support may also be
modified, for example, by treating it with sulfates, phosphates,
tungstenates, and silanes. For carbon supports, the carbon may be
pretreated with steam, oxygen (from air), inorganic acids or hydrogen
peroxide to provide more surface oxygen sites. The preferred pretreatment
would be to use either oxygen or hydrogen peroxide. The pretreated carbon
may also be modified by the addition of oxides of Group IVB and Group VB.
It is preferred to use oxides of titanium, vanadium, zirconia and
mixtures thereof.

[0063]The APR catalyst system may be prepared using conventional methods
known to those in the art. These methods include evaporative impregnation
techniques, incipient wetting techniques, chemical vapor deposition,
wash-coating, magnetron sputtering techniques, and the like. The method
chosen to fabricate the catalyst is not particularly critical to the
function of the invention, with the proviso that different catalysts will
yield different results, depending upon considerations such as overall
surface area, porosity, etc.

Oxygenated Compound Production

[0064]Various oxygenated compounds may be produced by the preferred
methods and reactor systems. For example, the reaction products may
include one or more diols or other polyols, ketones, aldehydes,
carboxylic acids and alcohols derived from the reaction of the in-situ
generated APR hydrogen with a portion of the remaining feedstock solution
over a second catalytic material, preferably a hydrogenation catalyst,
under conditions of reaction temperature, reaction pressure and weight
hourly space velocity (WHSV) effective to produce the desired reaction
products. The temperature and pressure are preferably selected to conduct
the reaction in the liquid phase. It is recognized, however, that
temperature and pressure conditions may also be selected to more
favorably produce the desired products in the vapor-phase. In general,
the reaction should be conducted at a temperature where the
thermodynamics of the proposed reaction are favorable. The pressure will
vary with the temperature and WHSV. For condensed phase liquid reactions,
the pressure within the reactor must be sufficient to maintain the
reactants in the condensed liquid phase at the reactor inlet.

[0065]For liquid phase reactions, the reaction temperature may be from
about 100° C. to about 300° C., and the reaction pressure
from about 72 psig to about 1300 psig. Preferably, the reaction
temperature is between about 120° C. and about 270° C., and
more preferably between about 200° C. and about 270° C. The
reaction pressure is preferably between about 72 and 1200 psig, or
between about 145 and 1200 psig, or between about 200 and 725 psig, or
between about 365 and 600 psig.

[0066]For vapor phase reactions, the reaction should be carried out at a
temperature where the vapor pressure of the oxygenated hydrocarbon
compound is at least about 0.1 atm (and preferably a good deal higher),
and the thermodynamics of the reaction are favorable. This temperature
will vary depending upon the specific oxygenated hydrocarbon compound
used, but is generally in the range of from about 100° C. to about
300° C. for vapor phase reactions.

[0067]The condensed liquid phase method of the present invention may also
be performed using a modifier that increases the activity and/or
stability of the catalyst system. It is preferred that the water and the
oxygenated hydrocarbon are reacted at a suitable pH of from about 1.0 to
about 10.0, including pH values in increments of 0.1 and 0.05 between,
and more preferably at a pH of from about 4.0 to about 10.0. Generally,
the modifier is added to the feedstock solution in an amount ranging from
about 0.1% to about 10% by weight as compared to the total weight of the
catalyst system used, although amounts outside this range are included
within the present invention.

[0068]In general, the reaction should be conducted under conditions where
the residence time of the feedstock solution over the catalyst is
appropriate to generate the desired products. For example, the WHSV for
the reaction may be at least about 1.0 gram of oxygenated hydrocarbon per
gram of catalyst per hour, and preferably between about 1.0 to 5.0 grams
of oxygenated hydrocarbon per gram of catalyst per hour, and more
preferably between about 1.9 to 4.0 grams of oxygenated hydrocarbon per
gram of catalyst per hour.

Hydrogenation Catalyst

[0069]The second catalytic material is preferably a heterogeneous
hydrogenation catalyst capable of catalyzing the reaction of hydrogen and
oxygenated hydrocarbons to produce the desired reaction products. The
preferred hydrogenation catalyst may include copper or at least one Group
VIIIB transition metal, and any alloys or mixtures thereof. The catalyst
may also be constructed to include either copper or at least one Group
VIIIB transition metal as a first metal, and at least one second metal
from the selection of Group VIIIB, Group VIIB, Group VIB, Group VB, Group
IVB, Group IIB, Group IB, Group WA or Group VA metals. The preferred
Group VIIB metal includes rhenium, manganese, or combinations thereof.
The preferred Group VIB metal includes chromium, molybedum, tungsten, or
a combination thereof. The preferred Group VIIIB metals include platinum,
rhodium, ruthenium, palladium, nickel, or combinations thereof. In one
embodiment, the preferred catalyst includes iron or rhenium and at least
one transition metal selected from iridium, nickel, palladium, platinum,
rhodium and ruthenium. In another embodiment, the catalyst includes iron,
rhenium and at least copper or one Group VIIIB transition metal.

[0070]The second catalytic material is preferably a hydrogenation catalyst
that is different from the first catalytic material, which is preferably
an APR catalyst, or a second catalyst capable of working in parallel with
or independently of the APR catalyst. The hydrogenation catalyst may also
be a bi-functional catalyst. For example, acidic supports (e.g., supports
having low isoelectric points) are able to catalyze dehydration reactions
of oxygenated compounds, followed by hydrogenation reactions on metallic
catalyst sites in the presence of H2, again leading to carbon atoms
that are not bonded to oxygen atoms. The bi-functional
dehydration/hydrogenation pathway consumes H2 and leads to the
subsequent formation of various polyols, diols, ketones, aldehydes and
alcohols. Examples of such catalysts include tungstated zirconia, titania
zirconia, sulfated zirconia, acidic alumina, silica-alumina, and
heteropolyacid supports. Heteropolyacids are a class of solid-phase acids
exemplified by such species as H3+xPMo12-xVxO40,
H4SiW12O40, H3PW12O40,
H6P2W18O62, and the like. Heteropolyacids are solid-phase
acids having a well-defined local structure, the most common of which is
the tungsten-based Keggin structure. The Keggin unit comprises a central
PO4 tetrahedron, surrounded by 12 WO6 octahedra. The standard
unit has a net (-3) charge, and thus requires 3 cations to satisfy
electroneutrality. If the cationic are protons, the material functions as
a Bronsted acid. The acidity of these compounds (as well as other
physical characteristics) can be "tuned" by substituting different metals
in place of tungsten in the Keggin structure. See, for example, Bardin et
al. (1998) "Acidity of Keggin-Type Heteropolycompounds Evaluated by
Catalytic Probe Reactions, Sorption Micro-calorimetry and Density
Functional Quantum Chemical Calculations," J. or Physical Chemistry B,
102:10817-10825.

[0071]Similar to the APR catalyst, the hydrogenation catalyst may be
adhered to a support as described above. The support may be the same
support as used for the APR catalyst or a support specific to the
hydrogenation catalyst as selected for the desired reaction outcome.

[0072]Preferred loading of the copper or primary Group VIIIB metal is in
the range of 0.25 wt % to 25 wt % on carbon, with weight percentages of
0.10% and 0.05% increments between, such as 1.00%, 1.10%, 1.15%, 2.00%,
2.50%, 5.00%, 10.00%, 12.50%, 15.00% and 20.00%. The preferred atomic
ratio of the second metal is in the range of 0.25-to-1 to 10-to-1,
including any ratios between such as 0.50, 1.00, 2.50, 5.00, and
7.50-to-1. In one embodiment, the hydrogenation catalyst includes iron
(Fe), a Group VIIIB metal, with an atomic ratio of Fe to the primary
Group VIIIB metal from 0.25-to-1 to 10-to-1. If the catalyst is adhered
to a support, the combination of the catalyst and the support is from
0.25 wt % to 10 wt % of the copper or primary Group VIIIB metal.

[0073]The heterogeneous catalyst may also be combined with the APR
catalyst to form a mixture so as to allow the APR reaction and the
hydrogenation reaction to occur simultaneously, or nearly simultaneously,
in a single reactor vessel. In such event, the recitation of a bimetallic
catalyst composition as "X:Y", where X is an APR catalyst and Y is a
hydrogenation catalyst, shall refer to a group of catalyst compositions
comprising at least APR catalyst X and hydrogenation catalyst Y, in any
suitable stoichoimetric combination and including other materials when
indicated. For example, the catalysts designated "Pt:Fe" includes the
mixture Pt1.0Fe1.0 and Pt2.5Fe1.0. Particularly
preferred catalysts include Pt1.0Ni1.0Fe1.0 and
Pt1.0Fe1.0Cu1.0, where Pt and Pt:Ni represent the APR
catalyst and Fe and Fe:Cu represent the hydrogenation catalyst.

[0074]The preferred atomic ratio of the APR catalyst (first catalytic
material) to the hydrogenation catalyst (second catalytic material) is in
the range of 5:1 to 1:5, such as, without limitation, 4.5:1, 4.0:1,3.5:1,
3.0:1, 2.5:1, 2.0:1, 1.5:1, 1:1, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5,
1:4.0, 1:4.5, and any amounts there between. For example, in one
embodiment, a catalyst mixture is provided the APR catalyst including
platinum and the hydrogenation catalyst including iron (Pt:Fe) at a ratio
of 1:1. If the catalyst mixture is adhered to a support, the combination
of the catalyst and the support may be from 0.25 wt % to 10 wt % of the
mixture.

[0075]The hydrogenation catalyst system, whether alone or mixed with the
APR catalyst, may be prepared using conventional methods known to those
in the art. Such methods include evaporative impregnation, incipient
wetting, chemical vapor deposition, wash-coating, magnetron sputtering
techniques, and the like. The method chosen to fabricate the catalyst is
not particularly critical to the function of the invention, with the
proviso that different catalysts will yield different results, depending
upon considerations such as overall surface area, porosity, etc.

Reactor

[0076]The reaction system can be configured such that the flow direction
of the aqueous feedstock solution can be selected to ensure maximal
interaction of the in-situ generated hydrogen with the feedstock
solution. For example, the reactor may be designed so that an APR
catalyst and a hydrogenation catalyst are stacked in a single reaction
vessel, or separated so that the APR catalyst and hydrogenation catalyst
are in separate reaction vessels. The reactor may also be designed to
accommodate multiple APR catalysts and hydrogenation catalysts so as to
allow for optimal production of more than one reaction product. The
reactor system may also include additional inlets to allow for the
introduction of supplemental materials to further advance or direct the
reaction to the desired reaction products, and to allow for the recycling
of reaction byproducts for use in the reforming process.

[0077]The reactor may be designed so that the feedstock solution flows
horizontally, vertical or diagonally to the gravitational plane so as to
maximize the efficiency of the system. In systems where the feedstock
solution flows vertically or diagonally to the gravitational plan, the
feedstock solution may flow either against gravity (up-flow system) or
with gravity (down-flow system). In one preferred embodiment, the reactor
is designed as an up-flow system such that the feedstock solution flows
through the reactor in an upwards direction. In this embodiment, the
feedstock solution first contacts a first reaction bed containing the APR
catalyst to produce APR hydrogen. Due to the configuration of the
reactor, the APR hydrogen is then able to, under certain conditions,
percolate through a second reaction bed containing the hydrogenation
catalyst at a rate greater than or equal to the feedstock solution to
maximize the interaction of the feedstock solution with the hydrogen and
hydrogenation catalyst.

[0078]In a reactor with a single chamber, the APR catalyst and
hydrogenation catalyst may be placed in a stacked configuration to allow
the feedstock solution to first contact the APR catalyst and then the
hydrogenation catalyst, or a series of hydrogenation catalysts depending
on the desired reaction products. The reaction beds for the APR catalyst
and hydrogenation catalyst, or catalysts, may also be placed side-by-side
dependent upon the particular flow mechanism employed, such as a
horizontal flow system. In either case, the feedstock solution may be
introduced into the reaction vessel through one or more inlets, and then
directed across the catalysts for processing. In the preferred
embodiment, the feedstock solution is directed across the APR catalyst to
produce APR hydrogen, and then both the APR hydrogen and the remaining
feedstock solution are directed across the hydrogenation catalyst, or
catalysts, to produce the desired reaction products. In embodiments
employing a mixture of APR catalyst and hydrogenation catalyst, the
generation of the APR hydrogen and the reaction products may occur
simultaneously or in parallel.

[0079]In a separate reactor configuration, the reactor may be designed to
allow for APR hydrogen production to occur in a reaction bed in one
reaction vessel with the reaction products generated in another reaction
vessel. The reaction vessels may be configured to run in parallel or
sequentially. In a parallel configuration, the feedstock solution may be
separated to direct a first portion of the feedstock solution to the
hydrogen reaction bed where APR hydrogen is produced, and a second
portion to a hydrogenation reaction bed where the desired reaction
products are produced using APR hydrogen generated by the hydrogen
reaction vessel. Alternatively, the reactor may be configured to
accommodate the use of two separate feedstock solutions, with the first
feedstock solution directed to the hydrogen reaction vessel and the
second feedstock solution directed to the hydrogenation reaction vessel.
In a sequential configuration, the reactor may be designed so that the
feedstock solution flows through the hydrogen reaction vessel and into
the hydrogenation reaction vessel. In either of these systems, because
the APR hydrogen is produced in-situ, the pressure is provided by a
pumping mechanism that also drives the feedstock solution through the
reactor chambers.

Supplemental Materials

[0080]Supplemental materials and compositions ("supplements") may be added
to the feedstock solution at various stages of the process in order to
enhance the reaction or to drive it to the production of the desired
reaction products. Supplements may include, without limitation, acids,
salts and additional hydrogen or feedstock. Such supplements may be added
directly to the feedstock stream prior to or contiguous with contacting
the hydrogenation catalyst, or directly to the reaction bed for the
hydrogenation reaction.

[0081]In one embodiment, the supplement may include an additional
feedstock solution for providing additional oxygenated hydrocarbons for
the hydrogenation reaction. The feedstock may include any one or more
oxygenated hydrocarbons listed above, including any one or more sugar
alcohols, glucose, polyols, glycerol or saccharides. For instance, the
supplemental material may include glycerol. In this embodiment, crude
glycerol is used to initiate the reaction and to produce hydrogen so as
to avoid polluting the hydrogenation catalyst with contaminants from the
crude glycerol. Purified glycerol is then added to the feedstock solution
prior to or at the same time the original feedstock solution is placed in
contact with the hydrogenation catalyst to increase the oxygenated
hydrocarbons available for processing. It is anticipated that the
opposite may be employed with the crude glycerol serving as the
supplement depending on the characteristics of the APR catalyst and
hydrogenation catalyst.

[0082]In another embodiment, the supplement may include byproducts of the
present invention recycled for further processing. The byproducts may
include diols, polyols, ketones, aldehydes, carboxylic acids, alcohols
and other products generated by the practice of the present invention.
For example, the desired reaction product of one embodiment of the
present invention is propylene glycol. However, the production of
propylene glycol may also result in the production of other polyols,
ketones, aldehydes, alcohols and carboxylic acids. The polyols may be
recycled and added back into the feedstock solution prior to contact with
the hydrogenation catalysts in order to provide supplemental oxygenated
hydrocarbons for conversion to propylene glycol. Similarily, ketones and
alcohols may be added to the feedstock solution prior to contact with the
APR catalyst to further supplement the production of hydrogen.

[0083]In yet another embodiment, the supplemental material may include
acids and salts. The addition of acidic compounds may provide increased
selectivity to the desired reaction products. In the preferred
embodiments, the water-soluble acid may include, without limitation,
nitrate, phosphate, sulfate, chloride salts, and mixtures thereof. If an
optional acidic modifier is used, it is preferred that it be present in
an amount sufficient to lower the pH of the aqueous feed stream to a
value between about pH 1.0 and about pH 4.0. Lowering the pH of a feed
stream in this manner may increase the proportion of diols, polyols,
ketones, alcohols or alkanes in the final reaction products.

[0084]In another embodiment, the supplement may include additional
hydrogen added to the feedstock solution to supplement the APR hydrogen
and to help drive the hydrogenation reaction to a desired reaction
product. The term "supplemental hydrogen" refers to hydrogen that does
not originate from within the feedstock, such as hydrogen added to the
feedstock from an external source. For example, supplemental hydrogen may
be added to the system for purposes of increasing the reaction pressure
over the hydrogenation catalyst, or to increase the molar ratio of
hydrogen to carbon and/or oxygen in order to enhance the production yield
of certain reaction product types, such as ketones and alcohols. The
supplemental hydrogen may be added at a molar ratio of supplemental
hydrogen to APR hydrogen at amounts no greater than 1:1, and preferably
no greater than 1:3, and more preferably no greater than 1:10, and still
more preferably no greater than 1:20. In the most preferred embodiment,
supplemental hydrogen is not added.

[0085]The amount of supplemental hydrogen to be added may also be
calculated by considering the concentration of oxygenated hydrocarbons in
the feedstock solution. Preferably, the amount of supplemental hydrogen
added should provide a molar ratio of oxygen atoms in the oxygenated
hydrocarbons to moles of hydrogen atoms (i.e., 2 oxygen atoms per
molecule of H2 gas) of less than or equal to 1.0. For example, where
the feedstock is an aqueous solution consisting of glycerol (3 oxygen
atoms), the amount of supplemental hydrogen added to the feedstock is
preferably not more than about 1.5 moles of hydrogen gas (H2) per
mole of glycerol (C3H8O3), and preferably not more than
about 1.25, 1.0, 0.75, 0.50 or 0.25. In general, the amount of
supplemental hydrogen added is preferably less than 0.75-times, and more
preferably not more than 0.67, 0.50, 0.33, 0.30, 0.25, 0.20, 0.15, 0.10,
0.05, 0.01-times the amount of total hydrogen (APR hydrogen and
supplemental hydrogen) that would provide a 1:1 atomic ratio of oxygen to
hydrogen atoms.

[0086]The amount of APR hydrogen within a reactor may be identified or
detected by any suitable method. The presence of APR hydrogen is
determined based on the composition of the product stream as a function
of the composition of the feedstock stream, the catalyst composition(s)
and the reaction conditions, independent of the actual reaction mechanism
occurring within the feedstock stream. The amount of APR hydrogen may be
calculated based on the catalyst, reaction conditions (e.g., flow rate,
temperature, pressure) and the contents of the feedstock and the reaction
products. For example, the feedstock may be contacted with the APR
catalyst (e.g., platinum) to produce APR hydrogen in situ and a first
reaction product stream in the absence of a hydrogenation catalyst. The
feedstock may also be contacted with both the APR catalyst and the
hydrogenation catalyst to produce a second reaction product stream. By
comparing the composition of the first reaction product stream and the
second reaction product stream at comparable reaction conditions, one may
identify the presence of APR hydrogen and calculate the amount of APR
hydrogen produced. For example, an increase in the amount of oxygenated
compounds with greater degrees of hydrogenation in the reaction product
compared to the feedstock components may indicate the presence of APR
hydrogen.

[0088]The specific reaction products produced by the practice of the
present invention will depend on various factors, including, without
limitation, the feedstock solution, water concentration, reaction
temperature, reaction pressure, the reactivity of the catalysts, and the
flow rate of the feedstock solution as it affects the space velocity (the
mass/volume of reactant per unit of catalyst per unit of time), gas
hourly space velocity (GHSV), and weight hourly space velocity (WHSV).

[0089]Preferably, the feedstock and reaction stream are contacted with the
first catalyst material and the second catalyst material, respectively,
at a weight hourly space velocity (WHSV) that is high enough to produce a
reaction product comprising one or more oxygenated hydrocarbons. It is
believed that decreasing the WHSV below about 0.5 grams of the oxygenated
hydrocarbons in the feedstock per hour may increase the amount of
hydrocarbons in the reaction products. Therefore, the WHSV is preferably
at least about 1.0 grams of the oxygenated hydrocarbons in the feedstock
per hour, more preferably the WHSV is about 1.0 to 5.0 g/g hr, including
a WHSV of about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4,
3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4,5, 4.6, 4.7, 4.8, 4.9
and 5.0 g/g hr. In one aspect, the feedstock comprises glycerol contacted
with a first catalytic material at a WHSV of about 1.9 or 4.0 g
glycerol/hour to produce a reaction product containing propylene glycol.

[0090]One skilled in the art will appreciate that varying the factors
above, as well as others, will generally result in a modification to the
reaction product yield. For example, an increase in flow rate, and
thereby a reduction of feedstock exposure to the catalyst over time, will
likely result in a decrease in the amount of hydrogen available for
hydrogenation over the hydrogenation catalyst. An increase in flow rate
may also limit the amount of time for hydrogenation to occur, thereby
causing increased yield for higher level diols and polyols, with a
reduction in ketone and alcohol yields.

[0091]One skilled in the art may also modify the conditions above to
enhance the efficiency of the system and improve the costs for
manufacturing the desired reaction products. For example, modification of
the water to oxygenated hydrocarbon ratio in the feedstock solution may
improve the overall thermal efficiency of the process by limiting the
need for external temperature controls. The process is thermally
efficient if the process is run at feed concentration of greater than 20%
by weight oxygenated compound, preferably greater than 30 wt %, more
preferably greater than 40 wt % and most preferably greater than 50 wt %.

[0092]In one preferred embodiment, the present invention provides a method
for producing a polyol from an aqueous feedstock solution comprising
glycerol. FIG. 2 shows the reaction schematic for the generation of
propylene glycol from glycerol with in-situ hydrogen generation. In the
reaction scheme of FIG. 2, a portion of the glycerol is reacted with
water under aqueous-phase reforming conditions to generate APR hydrogen
and carbon dioxide byproduct (Pathway 1 in FIG. 2). The stoichiometry for
Pathway 1 is shown in reaction 5 below:

C3H8O3 [glycerol]+3H2O→3CO2+7 H2 (5)

The generated APR hydrogen is then utilized for the
dehydration/hydrogenation reaction (Pathway 2 in FIG. 2) for the
selective generation of propylene glycol. The stoichiometry for Pathway 2
is shown in reaction 6 below:

C3H8O3 [glycerol]+H2→C3H8O2
[propylene glycol]+H2O (6)

In this step, a portion of the glycerol in the feedstock solution is
contacted with a portion of the APR hydrogen over a hydrogenation
catalyst under suitable aqueous phase reforming conditions to produce the
polyols, such as ethylene glycol and propylene glycol. In the preferred
embodiment, the combination of the two reaction pathways occurs according
to the overall reaction shown in reaction 7.

1.14C3H8O3→C3H8O2+0.43CO2+0.57H.-
sub.2O (7)

From this theoretical stoichiometry, 0.14 molecules of glycerol must be
reformed to generate enough APR hydrogen to hydrogenate one molecule of
glycerol to propylene glycol.

[0093]In another embodiment, the present invention provides a method for
producing an alcohol from an aqueous feedstock solution comprising
glycerol. FIG. 3 provides a schematic illustration showing a process for
converting glycerol to an alcohol with in-situ hydrogen generation. In
this process, glycerol is simultaneously (i.e., Steps 1 and 2 performed
concurrently over a single reactor bed) converted to APR hydrogen and an
alcohol (and other APR reaction products such carbon monoxide, carbon
dioxide, propylene glycol, methane, ethane, propane). The stoichiometry
for Pathway 1 is shown in reaction 8 below:

From this theoretical stoichiometry, 0.28 molecules of glycerol must be
reformed to generate enough APR hydrogen to hydrogenate one molecule of
glycerol to propyl alcohol.

[0094]In yet another embodiment, methods for producing an alcohol from an
aqueous feedstock solution comprising sorbitol are provided. FIG. 4 also
provides a schematic illustration showing a process for converting
sorbitol to an alcohol with in-situ hydrogen generation. In this process,
sorbitol is converted simultaneously (i.e., Steps 1 and 2 performed
concurrently over a single reactor bed) to hydrogen and an alcohol (and
other APR reaction products such as carbon monoxide, carbon dioxide,
methane, ethane, propane, butane, pentane, and hexane). The stoichiometry
for Pathway 1 is shown in reaction 11 below:

From this theoretical stoichiometry, 0.38 molecules of sorbitol is
reformed to generate enough APR hydrogen to hydrogenate one molecule of
sorbitol to hexanol.

[0096]One preferred method of generating an oxygenated compound comprises
the steps of: contacting a first catalytic material comprising one or
more Group VIII metals with a first portion of an aqueous feedstock
solution comprising water and at least one water soluble oxygenated
hydrocarbon having two or more carbon atoms, at: a temperature of about
80° C. to 400° C.; a weight hourly space velocity of at
least about 1.0 gram of the oxygenated hydrocarbon per gram of the first
catalytic material per hour; and a pressure where the water and the
oxygenated hydrocarbons are condensed liquids, to produce aqueous phase
reforming (APR) hydrogen; and reacting the APR hydrogen with a second
portion of the feedstock solution over a second catalytic material, the
second catalytic material different than the first catalytic material and
selected from the group consisting of: iron, ruthenium, copper, rhenium,
cobalt, nickel, alloys thereof, and mixtures thereof, at: a temperature
of about 100° C. to 300° C.; and a pressure of about 200
psig to about 1200 psig, to produce a reaction product comprising one or
more oxygenated compounds selected from the group consisting of a polyol,
a diol, a ketone, an aldehyde, a carboxylic acid and an alcohol. In one
aspect, the first portion of the feedstock solution and/or the second
portion of the feedstock solution are contacted with the first catalytic
material and the second catalytic material in a reactor vessel at a
temperature of about 200° C. to 270° C., including
210° C., 220° C., 230° C., 240° C.,
250° C., 260° C. and intervals of 1° C. between
200° C. and 270° C. In another aspect, the second portion
of the feedstock solution is contacted with the APR hydrogen and the
second catalytic material at a pressure greater than about 365 psig
(e.g., 365-1,200 psig), preferably greater than 400 psig (e.g., 478 psig
or 400-1,200 psig) or greater than 500 psig (e.g., 585 psig or 500-1,200
psig). The feedstock is preferably passed through a reactor at a weight
hourly space velocity (WHSV) selected to provide a product stream
comprising one or more oxygenated compounds, including at least one of: a
polyol, a ketone, an aldehyde, a carboxylic acid, and an alcohol. For
example the WHSV may be about 1.0 to 5.0 grams (including 1.0-4.0,
1.0-3.0, 1.0-2.0, 2.0-5.0, 3.0-5.0, 4.0-5.0 and any other interval of 0.1
therebetween) of the oxygenated hydrocarbon(s) in the feedstock per gram
of the catalytic mixture per hour.

[0097]Another preferred method of generating propylene glycol comprises
the step of contacting a heterogeneous catalyst system comprising one or
more Group VIII metals (e.g., one or more metals including platinum) and
a hydrogenation catalyst with an aqueous feedstock solution comprising
water and a water-soluble oxygenated hydrocarbon (e.g., glycerol or
sorbitol) at a temperature and pressure suitable to maintain the
feedstock in a liquid phase at (e.g., including temperatures of about
100° C. to 300° C.) at a weight hourly space velocity of at
least about 1.0 gram of the water-soluble oxygenated hydrocarbon per gram
of the heterogeneous catalyst per hour and a pressure where the feedstock
remains a condensed liquid to produce a reaction product comprising one
or more oxygenated compounds, such as a polyol (e.g., propylene glycol),
an aldehyde, a ketone, a carboxylic acid (e.g., lactic acid) and/or an
alcohol. The heterogeneous catalyst system may include a first catalyst
material containing a Group VIII metal or any suitable APR catalyst, and
a second catalyst containing a hydrogenation catalyst. The heterogeneous
catalyst system may be a catalytic mixture of the Group VIII metal and
the hydrogenation catalyst. The heterogeneous catalyst system may also be
two separate catalytic materials, including an APR catalyst and a
hydrogenation catalyst, contacted separately or together with the
feedstock. Preferably the heterogeneous catalyst system includes the
first catalytic material (e.g., an APR catalyst containing at least one
Group VIII metal) and the second catalytic material (e.g., a
hydrogenation catalyst) in a molar ratio of 5:1 to 1:5, including ratios
of 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4 and ratio intervals of 0.1 between
5:1 and 1:5.

[0099]In certain aspects of the preferred embodiments, the second
catalytic material is selected from one or more of the following groups:
iron, nickel, ruthenium, and cobalt; iron, ruthenium, and cobalt; iron,
nickel, and cobalt; iron, nickel, and ruthenium; nickel, ruthenium, and
cobalt; iron, nickel and ruthenium; and iron and cobalt. Preferably, the
second catalytic material is different from the first catalytic material.

[0100]Optionally, the first catalytic material and/or the second catalytic
material may be adhered to one or more suitable support materials, such
as a support with Bronsted acid sites. The support may comprise carbon.
Also optionally, the heterogeneous catalyst may consist essentially of
(or consist of) about 5 wt % iron and platinum in a molar ratio of about
1:1 on an activated carbon support; the feedstock may comprise at least
about 20 wt % (including 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, and
amounts of 1% therebetween) of one or more oxygenated hydrocarbon(s) such
as glycerol and/or sorbitol; the feedstock may be contacted with the
heterogeneous catalyst at a weight hourly space velocity of about 1.0 to
5.0 grams of glycerol per gram of the heterogeneous catalyst per hour and
a pressure of about 250-600 psig (including 300-600 psig, 300-1,200 psig,
365-600 psig, 365-1,200 psig, 400-600 psig, 478 psig, 478-1,200 psig, 585
psig and 585-1,200 psig); or the reaction product has a carbon yield of
propylene glycol of 40% or greater (including 50%, 60%, 70%, 80%, 90% or
greater). The amount of propylene glycol in the reaction product is
preferably at least about 5%, 10%, 20%, 30% or 40% of the amount of
liquid reaction product.

[0101]When present, the amount of supplemental hydrogen is preferably
provided sparingly. The feedstock is preferably substantially free of
supplemental hydrogen throughout the reaction process. Most preferably,
the amount of external supplemental hydrogen is provided in amounts that
provide less than one hydrogen atom per oxygen atom in all of the
oxygenated hydrocarbons in the feedstock stream prior to contacting a
catalyst. For example, the molar ratio between the supplemental hydrogen
and the total water-soluble oxygenated hydrocarbons in the feedstock
solution is preferably selected to provide no more than one hydrogen atom
in the supplemental (external) hydrogen per oxygen atom in the oxygenated
hydrocarbon. In generally, the molar ratio of the oxygenated
hydrocarbon(s) in the feedstock to the supplemental (external) hydrogen
introduced to the feedstock is preferably not more than 1:1, more
preferably up to 2:1, 3:1, 5:1, 10:1, 20:1 or greater (including 4:1,
6:1, 7:1, 8:1, 9:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1 and
19:1). The amount (moles) of hydrogen introduced to the feedstock from an
external source is preferably 0-30%, 0-25%, 0-20%, 0-15%, 0-10%, 0-5%,
0-2%, 0-1% of the total number of moles of the oxygenated hydrocarbon(s)
in the feedstock, including all intervals therebetween. Also preferably,
when the feedstock solution or any portion thereof is reacted with APR
hydrogen and an external hydrogen, the molar ratio of APR hydrogen to
external hydrogen is at least 3:1, including ratios of 5:1, 10:1, 20:1
and ratios therebetween (including 4:1, 6:1, 7:1, 8:1, 9:1, 11:1, 12:1,
13:1, 14:1, 15:1, 16:1, 17:1, 18:1 and 19:1).

[0102]In another embodiment, compositions of matter are provided. The
composition of matter may be found within a reactor system, including
within the reactor vessel and/or within a separator attached thereto. The
composition of matter may comprise water, glycerol, carboxylic acid,
carbon dioxide, propylene glycol, and a catalyst composition comprising a
first catalytic material and a second catalytic material as described
above. Preferably, the catalyst composition includes a Group VIII metal
and a hydrogen catalyst (e.g., platinum and iron).

[0103]In anther embodiment, reactor systems are provided. The reactor
system for producing oxygenated compounds from a polyol may include: a
first reaction bed adapted to receive an aqueous feedstock solution
comprising water and at least one water soluble oxygenated hydrocarbon
having two or more carbon atoms, the first reaction bed comprising a
first catalyst as described above configured to contact a first portion
of the feedstock solution in a condensed phase to form a reactant stream
comprising hydrogen; and a second reaction bed configured to receive the
reactant stream from the first reaction bed, the second reaction bed
comprising a second catalytic material as described above, and configured
to cause a reaction between the hydrogen and a second portion of the
feedstock solution to produce a product stream comprising one or more
oxygenated compounds selected from the group consisting of a polyol
(e.g., a diol), a ketone, an aldehyde, a carboxylic acid and an alcohol.

[0104]The following examples are included solely to provide a more
complete disclosure of the subject invention. Thus, the following
examples serve to illuminate the nature of the invention, but do not
limit the scope of the invention disclosed and claimed herein in any
fashion.

EXAMPLES

Example 1

Illustrative Reactor System 1

[0105]FIG. 5 is a schematic illustration showing one preferred process for
converting a feedstock solution 1 to a final desired product 12 using a
single reactor containing a catalyst composed of a mixture of the APR
catalyst and hydrogenation catalyst. The feedstock solution 1 includes
water combined with one or more oxygenated hydrocarbons, such as glycerol
or sugar alcohol. The feedstock solution 1 is combined with a recycle
stream 15 containing unreacted polyols, water, and byproducts of the
process, such as methanol and ethanol, from the process. The combined
stream 2 is fed via an HPLC pump (not shown) to reactor system 3 having
the APR/hydrogenation catalyst, where a portion of the stream reacts with
water over the catalyst to form APR hydrogen, which subsequently reacts
with the other portion of the stream over the hydrogenation catalyst to
generate the desired products.

[0106]The effluent stream 4 from the reactor 3 contains a mixture of
water, hydrogen, carbon dioxide, light hydrocarbons, light alcohols
(methanol and ethanol), diol product and unreacted glycerol. The mixture
is cooled and separated in a two-phase separator 5 where the
non-condensed gases (such as hydrogen, carbon dioxide, methane, ethane
and propane) are removed via stream 6 from the phase containing the water
soluble alcohols and diols. The non-condensable stream 6 can be either
combusted to create process heat (i.e., heat for driving the reaction in
reactor 3) or sent to a separation system where hydrogen can be recovered
for recycle back to stream 2. The aqueous stream 7 may be sent to a
separator 8 where the light alcohols (methanol and ethanol) and water are
removed and recycled back via stream 10 to the reactor inlet. A purge
stream 14 is included to prevent a build-up of water in the reactor
system.

[0107]A crude product stream 9, containing unreacted glycerol and desired
polyol, diol, ketone, aldehyde, carboxylic acid and/or alcohol products,
is recovered from separator 8 via stream 9 and sent to a finishing
separator where the desired product 12 is separated from unreacted
glycerol 13. The unreacted glycerol stream is then added to stream 10 and
recycled back to the reactor system via stream 15.

Example 2

Illustrative Reactor System 2

[0108]FIG. 6 is a schematic showing another preferred process for
converting a polyol feedstock solution 101 to a final diol product 114
using a reactor system that includes a first reactor bed 103 having an
APR catalyst and a second reactor bed 104 having a hydrogenation
catalyst. The feedstock solution 101 includes water combined with one or
more oxygenated hydrocarbons, such as sugar alcohol or glycerol.
Feedstock solution 101 is combined with a recycle stream 117 containing
unreacted polyols, water, and underdesirable byproducts (e.g., methanol
and ethanol). The combined stream 102 is fed via an HPLC pump (not shown)
to first reactor bed 103 where a portion of the stream reacts with water
over the APR catalyst to form APR hydrogen. The recycled alcohols
(methanol and ethanol) also react with water over the APR catalyst to
form APR hydrogen and light hydrocarbons, such as methane and ethane.

[0109]Effluent containing APR hydrogen, water, CO2, light
hydrocarbons and polyols move from first reactor bed 103 to second
reactor bed 104 where the APR hydrogen reacts with a portion of the
polyols to generate the desired products. In this illustration, the
reactor bed 103 and reactor bed 104 are set in an up-flow orientation to
allow the generated APR hydrogen to percolate from reactor bed 103
through second reactor bed 104 to maximize the interaction of APR
hydrogen and stream 102 over the hydrogenation catalyst. Reactor beds 103
and 104 may also be designed to accommodate down-flow or horizontal-flow
orientations.

[0110]The effluent stream 105 from the reactor system contains a mixture
of water, hydrogen, carbon dioxide, light hydrocarbons, light alcohols
(methanol and ethanol), diol and polyol products, and unreacted glycerol.
The mixture is cooled and separated in a two-phase separator 106 where
the non-condensable gases (such as hydrogen, carbon dioxide, methane,
ethane and propane) are removed via stream 107 from the phase containing
the water soluble alcohols, diols and polyols. The non-condensable stream
107 can be either combusted to create process heat or sent to a
separation system where hydrogen is recovered for possible recycle back
to stream 102. The aqueous stream 108 is sent to a separator 109 where
the light alcohols (methanol and ethanol) and water are removed and
recycled back via stream 110 to the reactor inlet. A purge stream 116 is
included to prevent a build-up of water in the reactor system.

[0111]A crude product stream 112, containing unreacted glycerol and the
desired polyol, diol and/or alcohol products, is recovered from separator
109 via stream 112 and sent to a finishing separator 113 where the
desired product 114 is separated from unreacted glycerol 115. The
unreacted glycerol stream is added to stream 110 and recycled back to the
reactor system via stream 117.

Example 3

Illustrative Reactor System 3

[0112]FIG. 7 is a schematic showing another preferred process for
converting a feedstock solution 201 to a final product 215 with the
introduction of a supplement 205. Supplement 205 may include various
salts, acids, additional feedstock solution, hydrogen or byproducts of
the process.

[0113]Feedstock solution 201 includes water combined with one or more
oxygenated hydrocarbons, such as glycerol or sugar alcohol. Feedstock
solution 201 may contain the same combination as feedstock solution 205
or a combination of one or more low cost oxygenated compounds, such as
waste methanol from a biodiesel process, ethylene glycol from spent
antifreeze, or low cost alcohols. Stream 201 may also be combined with
recycle stream 218, which contains unreacted polyols, water and
underdesirable byproducts, such as methanol and ethanol, to form combined
stream 202.

[0114]Combined stream 202 is fed via an HPLC pump (not shown) to reactor
bed 203 having an APR catalyst. Oxygenated hydrocarbons in combined
stream 202 react with water over the APR catalyst to form APR hydrogen,
while the recycled alcohols (i.e., methanol and ethanol) form hydrogen
and light hydrocarbons, such as methane and ethane.

[0116]The mixture is cooled and separated in a two-phase separator 208
where the non-condensable gases, such as hydrogen, carbon dioxide,
methane, ethane and propane, are removed via stream 209 from the phase
containing water-soluble polyols, alcohols and/or diols. The stream 209
can be either combusted to create process heat or sent to a separation
system where hydrogen can be recovered for possible recycle back to
stream 201 or used as a supplement 205.

[0117]Aqueous stream 210 is sent to a separator 211 where the light
alcohols (methanol and ethanol) and water are removed and recycled back
via stream 212 to the reactor inlet. A purge stream 217 is included to
prevent a build-up of water in the reactor system. A crude product stream
213 containing the desired product 215 and unreacted hydrocarbons is
recovered from separator 211 via stream 213 and sent to a finishing
separator 214 where the desired product 215 is separated from the
unreacted hydrocarbons 216. The unreacted hydrocarbon stream is added to
stream 216 and recycled back to the reactor system via stream 218 or used
as supplement 205.

Example 4

Illustrative Reactor System 4

[0118]The generation of polyols from glycerol is performed using the test
system illustrated in FIG. 8. The reactor in the system is configured in
a down flow orientation which improves contact of the aqueous feedstock
solutions with in-situ generated APR hydrogen as it flows through the
reactor.

[0119]Catalysts are loaded into a stainless steel tube reactor 1, which is
installed in an aluminum block heater 2 to maintain isothermal
conditions. The reaction temperature is controlled by the temperature
control subsystem. Some components of the temperature control subsystem
(not shown in FIG. 8) include a thermocouple inserted into the tube
reactor, resistive heaters mounted on the aluminum block, and a PID
controller.

[0120]Substrate solutions (i.e., feedstock solutions) can be selected to
be continuously fed into the reactor using an HPLC pump 3. The material
exiting the reactor is cooled as it passes through heat exchanger 4
before entering the phase separator 5.

[0121]Gasses exit the phase separator via the gas manifold 6, which is
maintained at constant pressure by the pressure control subsystem.
Components of the pressure control subsystem include: the pressure sensor
7, pressure control valve 8, and PID controller 9. The quantity of gas
released by the pressure control valve 8 is measured by mass flow meter
10. The composition of this gas is monitored by gas chromatography.

[0122]The liquid level in phase separator 5 is maintained at constant
level by the level control subsystem. The components of the level control
subsystem include the level sensor 11 in the phase separator, a level
control valve 12 and PID controller 13. The aqueous solution drained from
the phase separator during a catalyst evaluation experiment is collected
and the quantity collected measured gravimetrically. Analysis of this
solution may include, pH, total organic carbon concentration, GC to
determine the concentrations of unreacted substrate and specific
intermediates and side products.

Example 5

Preparation of Improved Carbon Support

[0123]Hydrogen peroxide was used to functionalize activated carbons to
provide improved supports for catalysts. See S. R. de Miguel, O. A.
Scelza, M. C. Roman-Martinez, C. Salinas Martinez de Lecea, D.
Cazorla-Amoros, A. Linares-Solano, Applied Catalysis A: General 170
(1998) 93. Activated carbon, 61 g, was added slowly to 1600 ml of 30%
hydrogen peroxide solution. After the addition of carbon was complete,
the mixture was left overnight. The aqueous phase was decanted and the
carbon washed three times with 1600 mL of DI water, then dried under
vacuum at 100° C.

[0125]The catalyst system described in Example 6 was tested in the
apparatus described in Example 4 using a feedstock solution containing 50
wt % glycerol. Prior to introducing the glycerol feedstock solution, the
catalyst was treated under flowing hydrogen at 350° C. The
reaction conditions were set at 240° C., 33.0 bar (478 psig), and
WHSV of 4.0 grams glycerol per gram of catalyst per hour. The glycerol
conversion was 64%. This experiment was repeated with a second feedstock
solution containing 50 wt % glycerol and 50% water feed over the catalyst
of Example 6 the following reaction conditions: 260° C., 40.3 bar
(585 psig), WHSV of 1.9 grams glycerol per gram of catalyst per hour.

[0126]At the low temperature regime, pressures and catalyst amounts used
were all commercially viable conditions for the APR process. The glycerol
conversions for these two cases were 64% and 88% of the theoretical
maximum, respectively. FIG. 9 summarizes the yield of carbon containing
products, and shows the selectivity of the conversion of glycerol to the
carbon-containing products for the high and low temperature reactions.
The graph shows that propylene glycol was the major product generated,
followed by carbon dioxide (a byproduct of the in-situ generation of APR
hydrogen), ethanol, and ethylene glycol. The gas phase alkanes included
methane, ethane, and propane, with methane being the most abundant
gas-phase alkane.

[0127]The results confirm that it is possible to generate propylene glycol
in reasonable yields via liquid-phase reforming of aqueous solutions of
glycerol, and that it is possible to generate significant or predominant
amounts of propylene glycol from glycerol with in-situ generated hydrogen
and, preferably, without concurrently introducing hydrogen from an
external source. The presence of byproducts from the hydrogen generation
process surprisingly did not significantly impact the ability of the
glycerol conversion to propylene glycol and other products.

[0128]The described embodiments and examples are to be considered in all
respects only as illustrative and not restrictive, and the scope of the
invention is, therefore, indicated by the appended claims rather than by
the foregoing description. All changes which come within the meaning and
range of equivalency of the claims are to be embraced within their scope.